With the development of display technology, touch panels are gradually spread and widely applied to products such as mobile phones, tablet computers, notebook computers and so on.
Currently, touch panels can be divided into resistive type, capacitive type, infrared type, surface acoustic wave type and the like according to the working principle, and can be divided into add-on touch panels, on-cell touch panels, in-cell touch panels and the like according to the structure. For instance, an add-on touch panel is a touch panel having touch function in which a touch screen and a display panel are separately produced and bonded together. The add-on touch panel has the defects of high production cost, low transmittance, large module thickness and the like. An in-cell touch panel is obtained by combining touch electrodes of a touch panel into, for instance, a liquid crystal display (LCD), not only can reduce the overall thickness of a module but also can greatly reduce the production costs of the touch panel, and hence is favored by major panel manufacturers.
Currently, a capacitive in-cell touch panel can be obtained by additionally disposing touch drive electrodes and touch sensing electrodes in a thin-film transistor liquid crystal display (TFT-LCD) panel. For instance, indium tin oxide (ITO) strip electrodes disposed on different layers and intercrossed with each other are manufactured on a surface of a TFT array substrate. The two layers of ITO strip electrodes are respectively used as touch drive electrodes and touch sensing electrodes for achieving the touch function.
FIG. 1 is a schematic diagram showing the capacitance produced between a touch drive electrode and a touch sensing electrode. As illustrated in FIG. 1, mutual capacitance Cm is produced between the touch drive electrode Te disposed on the upper portion and along one direction and the touch sensing electrode Re disposed on the lower portion and along the other direction. FIG. 1 is a sectional view perpendicular to the extension direction of Te. For instance, when a screen is touched by a finger, because the human body is of conductor, the touch of the finger will change the mutual capacitance Cm. A touch detecting device can determine whether there is touch and detect the position of the finger touch point by detecting the variation of current corresponding to the mutual capacitance Cm before and after the finger touch.